Imprinting webs of material is an old art that has undergone major changes in the last century. One of the disadvantages of the high speed with which the webs are imprinted is the difficulty or sheer inability to manually inspect the surface or surfaces of such webs for contaminants. This inability to inspect can result in unacceptably high customer returns. These problems can be especially pronounced in the food and medical packaging industries.
One alternative is to provide an automated inspection system that can scan the surfaces, looking for the contaminants either on the surface, or within the surface, in the case of a laminated film web. The particular contaminants that are of concern are carbon particles, poly gels, insects or insect parts, dirt or other matter. The desired sensitivity of contaminant detection would be in the range of 0.4 square millimeters on a web of up to 48 inches wide moving at speeds of up to 1000 feet per minute.
Single film webs usually do not present much problem for scanning for contaminants, since they are easily scanned prior to printing. However, the device of the present invention provides capability of scanning after lamination and printing of laminated films, particularly where the contaminant can be captured between the film layers during the imprinting or laminating process.